1. Field of the Invention
The invention herein relates to golf club shafts. More particularly it relates to shafts formed of composites of fiber reinforced resin/polymer.
2. Description of the Prior Art
Golf club shafts made of fiber reinforced resin, particularly resin reinforced with carbon fibers, have been popular for several years. Many players prefer them over the conventional metal shafts. There is commonly a delicate subjective balance among flex, torque and stiffness in a golf club shaft, such that if a player does not think that the balance is "right" the player is not comfortable with the "feel" of the club and finds his or her golf swing impaired to some degree. This is particularly marked with the better players, i.e. those from the professional and low handicap amateur ranks. Such players are extremely demanding about the precise degree of desired flex and stiffness balance in the clubs they use. Since the "right" amount of balance between flex and stiffness is highly subjective to each player, players will commonly use and discard a number of different clubs or sets of clubs seeking to find the set that has a "comfort zone" within which the shaft provides the balance of flex, torque and stiffness with which the player individually feels the most comfortable. Unfortunately, since it has been difficult to obtain the desired balance of flex, torque and stiffness of such composite shafts other than by costly custom design of shafts for individual players, volume manufacturers of shafts have not been able to provide club shafts which would allow for a variety of shafts of different feel on a commercial scale.
Also, a very severe problem with composite resin/fiber shafts has been there tendency to crack or break at the point where the shaft joins the hosel of the club head. In the past, shafts made with a relatively small diameter to provide greater feel also were the most likely to break. This required shaft manufacturers to produce "fat" shafts for added strength, but these bulky shafts are decidedly stiff and do not provide the feel most players want.
Further, the shape of the end of the shaft and its fit with the hosel have been problems. Current shaft designs provide a relatively small contact area between the shaft tip and hosel, so it is difficult to obtain accurate and consistent alignment between the shaft and the club head through the hosel.
It would therefore be of significant advantage to have a fiber reinforced composite golf club shaft design which could be manufactured on a large scale commercial basis, which could be produced in a variety of combinations of flex, torque and stiffness, and which was virtually free of any tendency to break.